Ignition system for a parachute flare

ABSTRACT

An ignition system for air dropped illuminating flares or the like, including a cord attached to a parachute which exerts a shock force. The other end of the cord is attached to a bell crank which is rotated when the parachute opens causing a firing pin to strike a primer which ignites some pellets causing a wafer of polymer type ignition propellant to ignite. The flare illuminant is then ignited and emits the required smoke and flame signal as the flare floats downward to earth.

United States Patent 1 Roberts et al.

[54] IGNITION SYSTEM FOR A PARACHUTE FLARE [75] Inventors: Henry J. Roberts, Roy; James R.

Thurston, Perry; Vern Thomas Dinsdale, Brigham City, all of Utah 22 Filed: Sept. 10,1970

21 Appl.No.: 70,968

[ 1 June 5,1973

1,832,855 ll/l93l Bok 102/35 3,352,244 l l/l967 Holter et al l02/l03 2,340,047 1/1944 Dunn 102/35 Primary ExaminerBenjamin A. Borchelt Assistant Examiner-Daniel A. Bent Attorney-Harry A. Herbert, Jr. and Arsen Tashjian [57] ABSTRACT An ignition system for air dropped illuminating flares or the like, including a cord attached to a parachute which exerts a shock force. The other end of the cord is attached to a bell crank which is rotated when the parachute opens causing a firing pin to strike a primer which ignites some pellets causing a wafer of polymer type ignition propellant to ignite. The flare illuminant is then ignited and emits the required smoke and flame signal as the flare floats downward to earth.

3 Claims, 1 Drawing figure [52] US. Cl ..l02/3S, 102/20 [5 1] Int. Cl ..F42b 13/38 [58] Field of Search ..l02/35, 20

[56] References Cited UNlTED STATES PATENTS 1,686,117 lO/l928 Ball ..lO2/35 Id n a ll 2s 4 v I If 7 IGNITION SYSTEM FOR A PARACHUTE FLARE BACKGROUND OF THE INVENTION ignition system which can only be triggered by the parachute shock opening force and which includes a foam plastic element for absorbing impact energy to prevent inadvertent ignition of the flare if it should be accidentally dropped on the ignition end.

In modern flare technology, one of the most significant considerations is overall safety especially during handling and deployment of the flare. This requirement is particularly important in aircraft-launched parachute suspended illuminating flares which are generally used for signalling. In operation, the flare should be safe to handle and not subject to accidental ignition. At the same time, the flare should be dependable, that is, it should be reliable and ignite under the proper condition but not ignite if accidentally dropped.

The ideal parachute flare would be one which would be triggered by the chute shock opening force during deployment. The application of impact or shock loads, such as would result from a drop of forty feet, should not produce inadvertent ignition of the flare. Of course, it would be desirable to be able to trigger the flare when it is disassembled by a pull on the ignition lanyard similar to that exerted by the chute opening force which would exceed 30 pounds.

SUMMARY OF THE INVENTION The present invention provides a flare ignition system which is suitable for use to ignite an aircraftlaunched parachute suspended illuminating flare and can be used for rocket deployed or other ordnance ground flare type equipment, such as colored markers, gas generators, etc. The ignition system operates in response to the parachute shock opening force during flare deployment by pulling an ignition lanyard which triggers a firing pin subassembly. This produces a chain reaction by igniting a rifle primer, nitrate pellets and polymer propellant which, inturn, ignites the flare illuminant. The ignition propellant is housed in foam plastic to absorb any impact energy which would occur if the flare were inadvertently dropped on the ignition end, thereby adding significantly to the safety of the device.

Accordingly, it is an object of the invention to provide a flare ignition system which may be used to ignite an aircraft-launched parachute suspended illuminating flare or the like.

Another object of the invention is to provide a flare ignition system which can only be triggered by the parachute shock opening force during flare deployment.

Still another object of the invention is to provide a flare ignition system using materials which far exceed the safety and environmental requirements while offering reliability well above the specified level.

A further object of the invention is to provide an ignition system for an illuminating flare which is airdropped. As the parachute opens, a cord is pulled, releasing a firing pin which ignites other ignition components causing the flare illuminant to ignite andundergo progressive combustion.

These and other objects, features and advantages will become more apparent after considering the following description taken in conjunction with the annexed drawing and the appended claims.

DESCRIPTION OF THE DRAWING In the drawing:

The FIGURE shown is a view in cross-section of the flare ignition system according to the invention showing the firing pin subassembly including the bellcrank, both before and in phantom immediately after release of the firing pin prior to spring biased movement toward the rifle primer.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawing, there is shown in cross-section a flare ignition system which includes a lanyard 13 having one end fixedly attached to a parachute support cable 15 by means of a crimp type fitting 17. The other end of the lanyard 13 is attached to a bellcrank 19 which is arranged to rotate around the pivot pin 21 when the lanyard 13 is pulled with a jerk as the parachute opens. A shear pin 23 prevents the bellcrank 19 from rotating until sufficient force is exerted on the lanyard 13.

The rotation of the bellcrank 19 operates to pull down the firing pin 25 by engaging the lower end thereof. The firing pin 25 is positioned in the housing 27 along with the compression spring 29 which is compressed when the firing pin 25 is pulled downward. As the bellcrank 19 is rotated further by the pulling action of the lanyard 13, the firing pin 25 is disengaged form the bellcrank l9 and the compression spring 29 causes it to be forced upward against a primer 31 which may be, for example, a conventional large rifle primer. In the area immediately above and adjacent to the primer 31, there is disposed at small amount of highly flammable pelletized material 33, such as boron potassium nitrate, which is ignited from the heat and flame output of the primer 31.

Laterally adjacent to and in operative communication with the pelletized material 33, there is positioned a wafer of polymer type of ignition propellant 35. This propellant 35 is ignited by the combustion output of the pelletized material 33. A piece of plastic foam 37, such as polystyrene, is positioned around the sensitive ignition propellant 35 to protect it by absorbing the impact shock if the flare should be inadvertently dropped on the ignition end.

The entire ignition end including the firing pin subassembly is enclosed in the housing 39 made of aluminum alloy or plastic. The ignition system assembly is then installed in the flare case 41 by crimping the flare case 41 into an 0-ring 43 creating an environmental sealed structural joint. The flare illuminant 45 is positioned to receive the heat and flame output of the ignition propellant 35 which operates to ignite the illuminant 45 and cause it to burn while the parachute is floating earthward.

In operation, a timer mechanis minot shown) that also acts as an end closure goes through its present time cycle that serves to release and pull the parachute. The parachute shock opening force acting on the support cable during flare deployment pulls the ignition lanyard 13 which rotates the bellcrank 19 around the pivot pin 21 after causing the shear pin 23 to fail. The firing pin 25 is pulled downward compressing the spring 29. As the bellcrank 19 reaches full ravel position 29 (not shown) in phantom), the firing pin 25 escapes in the energy in the compressed spring 29 drives the firing pin 25 into a standard type rifle primer 31. The heat and flame output from the rifle primer 31 ignites a few grams of boron potassium nitrate pellets 33 or the like which, in turn, ignites a wafter of solid ammonium perchlorate HB polymer type ignition propellant 35. A suitable HB polymer would be any known type of polymer used as the fuel-binder component in solid propellants. For example, it may be an acrylo-butadiene polymer which is a liquid terpolymer of butadiene, acrylic acid and acrylonitrile and which may be made by the process disclosed in US. Pat. No. 3,563,966. This illustrative propellant is made by mixing the liquid terpolymer with finely divided ammonium perchlorate and a suitable curing agent such as polyepoxide and heat-curing the mixture to form a dispersion of ammonium perch lorate particles in a rubber-like matrix. The flare illuminant 45 is ignited from the output of the ignition propellant 35.

The ignition propellant 35 is housed with in a piece of polystryrene foam 37 which functions to hold the propellant 35 in position as well as to absorb a great amount of the impact energy and provide a built-in safety factor for the flare ignition system. As a matter of fact, the ignition system as hereinbefore disclosed is configure d to pass the forty foot drop test and other impact and shock loads as required by present military standards preventing inadvertent ignition.

Although the invention has been illustrated in the accompanying drawing and described in the foregoing specification in terms of a preferred embodiment thereof, the invention is not limited to this embodiment or to the particular configuration mentioned. It will be apparent to those skilled in the art that our flare ignition system could have extensive use in other operations where it is desired to provide a safe and reliable ignition system for other ordnance ground flare type equipment.

Having thus set forth and disclosed the nature of our invention; what we claim and desire to secure Letters Patent of the United States is:

l. A flare ignition system for igniting an aircraft launched parachute suspended illuminating flare, said ignition system comprising, a first housing, a bellcrank disposed in said first housing for rotation around a pivot pin, a lanyard having one end attached to said bellcrank and the other end fixedly attached to said bellcrank and the otherend fixedly attached to the parachute support cable, a firing pin disposed in said first housing for vertical movement therethrough means on the lower end of said firing pin for engaging said bellcrank to produce initial downward movement of said firing pin in response to the pulling of said lanyard, a compression spring positioned around said firing pin for urging said firing pin upward, said compression spring being loaded by the downward movement of said firing pin, said bellcrank being arranged to release said firing pin after full downward travel to permit said compression spring to drive said firing pin upward, a second housing disposed in the flare causing for containing said first housing and the elements therein, a primer positioned in said second housing above and in axial alignment with said firing pin flammable pelletized. material disposed in said second housing immediately above said primer for ignition therefrom, a wafer of polymer type ignition propellant juxtaposed said pelletized material for ignition from the output thereof, plastic foam means for protecting said ignition propellant from shock positioned therearound, and flare illuminant positioned near said ignition propellant to receive the heat and flame output therefrom, thereby igniting the flare in response to the parachute shock opening force applied to said lanyard attached to the parachute support cable.

2, The flare ignition system defined in claim 1 wherein said flammable pelletized material ignited by the output from said firing pin is boron potassium nitrate.

3. The flare ignition system defined in claim 2 wherein said wafer of polymer type ignition propellant ignited by said boron potassium nitrate pellets is solid ammonium perchlorate HB polymer. 

1. A flare ignition system for igniting an aircraft launched parachute suspended illuminating flare, said ignition system comprising, a first housing, a bellcrank disposed in said first housing for rotation around a pivot pin, a lanyard having one end attached to said bellcrank and the other end fixedly attached to said bellcrank and the other end fixedly attached to the parachute support cable, a firing pin disposed in said first housing for vertical movement therethrough means on the lower end of said firing pin for engaging said bellcrank to produce initial downward movement of said firing pin in response to the pulling of said lanyard, a compression spring positioned around said firing pin for urging said firing pin upward, said compression spring being loaded by the downward movement of said firing pin, said bellcrank being arranged to release said firing pin after full downward travel to permit said compression spring to drive said firing pin upward, a second housing disposed in the flare causing for containing said first housing and the elements therein, a primer positioned in said second housing above and in axial alignment with said firing pin flammable pelletized material disposed in said second housing immediately above said primer for ignition therefrom, a wafer of polymer type ignition propellant juxtaposed said pelletized material for ignition from the output thereof, plastic foam means for protecting said ignition propellant from shock positioned therearound, and flare illuminant positioned near said ignition propellant to receive the heat and flame output therefrom, thereby igniting the flare in response to the parachute shock opening force applied to said lanyard attached to the parachute support cable.
 2. The flare ignition system defined in claim 1 wherein said flammable pelletized material ignited by the output from said firing pin is boron potassium nitrate.
 3. The flare ignition system defined in claim 2 wherein said wafer of polymer type ignition propellant ignited by said boron potassium nitrate pellets is solid ammonium perchlorate HB polymer. 